Hey, Where's the Hot Water?

In many ways, new homes may be experiencing the best of times. But for their hot water distribution systems it can be the worst of times.

It is 6 am on a workday. Picture yourself standing before the master bath lavatory in your brand-new home with the faucet on full getting ready to shave. Minutes pass as you await the arrival of hot water to help you awake and ease the shave.This scene is being played out throughout the nation in new homes, even energyefficient ones, as a combination of factors converge to give the homeowner longer waits for hot water and higher energy,water, and sewer bills (see “The Worst of Times for New Hot Water Distribution System Efficiency,” p. 38). The Oak Ridge National Laboratory (ORNL) studied hot water distribution systems for the California Energy Commission using a newly developed model to simulate the performance impact of a number of hot water distribution system parameters (see “Are You Getting into Hot Water?” HE Sept/Oct ’03, p. 33).This article looks at the results from three distinctly different residences and evaluates changes to conventional trunk and branch distribution systems —a large-diameter trunk from the water heater serving small-diameter branches to individual fixtures. Our evaluation included &...